Published German patent application 3,708,289 discloses a work apparatus such as a chain saw wherein the cooling air is drawn in axially by a fan wheel. The cooling air is moved by the vanes of the fan wheel in a radial direction and flows via a cooling-air spiral in the direction toward the internal combustion engine. An air-guiding wall is disposed parallelly to the outlet diameter of the fan wheel and surrounds the inlet opening of an air channel extending in the rotational direction of the fan wheel and by means of which the combustion air is tapped into an air chamber. A considerable quantity of dirt particles is drawn in with the cooling air and the channel extends tangentially from the fan wheel in the direction of rotation. For these reasons, the dirt particles enter into the air channel and into the carburetor enclosure where they must be filtered by an air filter. An air filter of this kind will therefore become clogged with dirt particles very quickly and must be cleaned after a short operating time and, under some circumstances, even be exchanged.